Images 1 & 2: Axial T2 weighted images of brain reveal a well defined
midline hyperintense lesion of comparable signal to CSF. It is located
posterior to the third ventricle and anteromedial to both occipital horns.
Image 3: Axial proton density weighted image shows the lesion as intermediate signal
area and isointense to CSF.
Image 4: Coronal T1 weighted image demonstrates the lesion as low signal area lying
beneath the corpus callosum and above the midbrain.
Image 5: Sagittal T1 weighted image shows lesion lying anteroinferior to the splenium
of corpus callosum. The quadrigeminal plate is slightly indented by the lesion. (T. Lai)
Key words: mri tumor neoplasm
Cavum velum interpositum
or arachnoid cyst of the
cisterna velum interpositum